1. Field of the Invention
The invention relates to a shift control apparatus for vehicular continuously variable transmissions and, more particularly, to a shift control apparatus for performing in an improved manner changeover control from a manual shift mode, in which changes in change gear ratio are made stepwise in accordance with an operation by a driver, to an automatic shift mode.
2. Description of the Related Art
Japanese Patent Application Publication No. 2006-97789 (JP-A-2006-97789) describes a shift control apparatus for vehicular continuously variable transmissions that has a continuously variable transmission disposed between a running power source and driven wheels and designed to allow continuous changes in change gear ratio, and manual shift control means for changing the change gear ratio of the continuously variable transmission in accordance with an operation by a driver among a plurality of change gear ratios set stepwise in advance. According to this art, a temporary manual shift mode, in which the change gear ratio of the continuously variable transmission is changed stepwise to any one of the plurality of the change gear ratios designated in advance in response to a manual shift operation by the driver, is realized. Also, when one of cancellation conditions that the acceleration of a vehicle remain equal to or lower than a predetermined acceleration for a predetermined time or more, that an accelerator pedal remain open for a predetermined time or more, and that the speed of the vehicle be equal to or lower than a predetermined speed is fulfilled, the above-mentioned temporary manual shift mode is canceled and changed over to an automatic shift mode. A changeover from the manual shift mode to the automatic shift mode can thereby be made desirably without causing the driver a sense of incongruity.
In the aforementioned art, however, the vehicle may not be accelerated as intended by the driver owing to hold control of a shift stage (change gear ratio) when the driver depresses the accelerator pedal while running in the temporary manual shift mode. Therefore, there are demands for the development of a shift control apparatus for vehicular continuously variable transmissions that performs changeover control from a manual shift mode to an automatic shift mode in accordance with an accelerating intention of a driver.